1986 Pontiac Fiero Engine Swap--Will Not Start

Tiny
CARNORUNNY
  • MEMBER
  • 1986 PONTIAC FIERO
Electrical problem
1986 Pontiac Fiero 6 cyl Two Wheel Drive Manual

I replaced the motor in my Fiero and have not got it to fire. There is good spark to each cylinder. There is 45 PSI fuel pressure to the fuel rail. The replacment motor is an exact copy of original motor. Estimating motor to have 120,000 miles on it and has not been in a running vehicle for quite a few years. Everything seems to be in good order, just won't start. I do not believe the injectors are spraying fuel because plugs are always dry as a bone. To elimate bad injectors, I swithced out injectors from original motor. I have also swapped out a buch of sensors. Still nothing.

I am wondering if I have a wiring issue because the wiring harness on this motor I picked up was cut, rather than unplugged. So, I simply spliced the harnesses together with crimp type connectors. Every wire matched so I did not think it would be a problem. I am now wondering if I should solder the wires instead. I have also added a bunch of grounds in random places. Maybe the ECM?

The motor itself seems to have good compression and turns over quite nicely.

I am baffled on this one. I am extremely appreciative of any help I can get with this. Thanks guys.
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Monday, September 28th, 2009 AT 8:12 PM

7 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
If all the wires matched and you crimped them together, that should be fine. Now, will the engine start with starting fluid? Also, have you checked for an injector pulse with a noid light?
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Monday, September 28th, 2009 AT 8:28 PM
Tiny
CARNORUNNY
  • MEMBER
No, the motor acutally will not fire with starting fluid. I have tried it a few times and not even a pop.

I have a noid light but am unsure of how to check the pulse to the injectors. I know there is that 6 pin connector that feeds the injectors. The ecm sends a ground signal to the injectors right? Would that mean I have to hook the noid light up to a positive or would I still ground it as usual? I read that I should unhook the 6 pin connector and test each wire for the signal? I do this while turning motor over right? I really dont think they are getting a signal but I will definately go out and try that as soon as you let me know the proper steps to take. Thanks a bunch!
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Monday, September 28th, 2009 AT 8:43 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Ground the light and test each pin for a pulse while cranking the engine. However, if it doesn't start with starting fluid, something tells me you're not getting spark or not a hot enough spark. But, you said the plugs were dry which doesn't make sense.

LEt me know what you find with the injector pulse.
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Monday, September 28th, 2009 AT 9:00 PM
Tiny
CARNORUNNY
  • MEMBER
I tested the 6 pins. They are marked A-F left to right

A:light pink/white
Steady on while key on and while cranking
B:green
Nothing
C:blue
Nothing
D:pink
Steady on while key on and while cranking
E:big pink/white
Steady on while cranking. Nothing with key on.
F:brownish
Nothing

I also went ahead and sprayed engine start while cranking and was surprised to find that the engine did in fact pop quite a bit. Sounded as if it would almost start. Never did run though. I tried engine start a few months ago and never recalled anything happening, but its poppin now.

Much appreciation. Thank you.
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Monday, September 28th, 2009 AT 10:34 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Did any of them pulse?
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Tuesday, September 29th, 2009 AT 8:06 AM
Tiny
CARNORUNNY
  • MEMBER
No pulsing what so ever. The light would just stay on constant.
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Tuesday, September 29th, 2009 AT 4:26 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Either the PCM (computer) is bad or you have a bad connection. Wiggle the wiring harness to the computer and see if anything changes. Also, make sure everything is connected. You may have missed something or bumped something when changing the engine.
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Tuesday, September 29th, 2009 AT 9:15 PM

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